The "Ask a Mechanic" Thread (merged)

[SpringfieldSkins]

I have the following situation.

2000 kia spectra

After driving for a while (car is sufficiently warmed up) and coming to a complete or near complete stop, my vehicle will backfire out of the tailpipe for about 5 seconds (not long). It is not loud or very noticeable but if it goes on for a couple of seconds the idle will drop and the car will sputter. It does not do it all the time but here the situations where it can happen:

1. Cool-cold days
2. Cool rainy days (never noticed while warm-hot outside)
3. When complete stop or slowing while going up a hill.

More info...
About 1 year ago I got the spark plug holes wet and the car ran poorly. I ended up changing the plugs but not the wires (never in stock in my area). I tested the resistance of the ignition coils and they seemed within spec.

HEELLLLLP!


p.s. What are everyone's opinion of "performance rotors" i.e. cross drilled slotted or over-sized rotors?

My thought is that it is an ignition break down or a problem with the idle air control motor. I'm leaning more towards the idle air control because an ignition based misfire usually happens when accelerating or under a load. You could easily wet down the coil and wires and see if there is any sort of a misfire, that would eliminate the possibilities fast. The idle air control (or MAF sensor) would be more of a likelihood because it happens when the engine is coming back to idle.


As far as performance rotors... you won't notice much of a difference unless you are doing some heavy braking. The main goal is to dissipate as much heat as possible and slotting or drilling the rotor allows for air to vent out. If you are using the rotor beyond its capability, you will encounter brake fade, where the pedal will sink down. The rotor/pad/caliper will get so hot that the brake fluid will boil, causing the pedal to sink down as the fluid expands (which it shouldn't). If you don't encounter brake fade, you aren't using the brake rotor past its true capability.

As far as the "big brake" rotor kits. They replace the rotors with larger diameter rotors. They also replace the pads with larger pads and more powerful calipers. Big brake kits are outrageously expensive and only really only necessary if you are doing some serious racing.

[SpringfieldSkins]

The power lock on the passenger side of my Ford Explorer no longer works. The buttons all work, but the actual lock itself on that side seems as if its not catching or something. Any thoughts on how to fix without paying out the ass?

My thought is the actuator. They fail all the time on those cars. We had an Explorer in the shop just last week that needed two at the same time.

[SpringfieldSkins]

Springfieldskins,

Thanks , it was a bad connection ( dirty) , says the mechcanic i took the van to. To fix the connection and take the dash apart to unstick the needles was $138 which i thought was a fair price.

Cool. Glad you got it fixed and it wasn't super expensive. The price you paid seems fair to me.

[mark327]

My thought is the actuator. They fail all the time on those cars. We had an Explorer in the shop just last week that needed two at the same time.

When i put my wife's Ford mini van in the shop for the dash problem . i noticed that her drivers side electric door lock was not working. I had them fix that as well . Parts and labor was $200 . Not sure if that was a fair price or not , but now i have to figure on $400 to have my Excurison's 2 passengers side doors repaired , neither of those are working right now either

[Buford T. Justice]

My thought is that it is an ignition break down or a problem with the idle air control motor. I'm leaning more towards the idle air control because an ignition based misfire usually happens when accelerating or under a load. You could easily wet down the coil and wires and see if there is any sort of a misfire, that would eliminate the possibilities fast. The idle air control (or MAF sensor) would be more of a likelihood because it happens when the engine is coming back to idle.


As far as performance rotors... you won't notice much of a difference unless you are doing some heavy braking. The main goal is to dissipate as much heat as possible and slotting or drilling the rotor allows for air to vent out. If you are using the rotor beyond its capability, you will encounter brake fade, where the pedal will sink down. The rotor/pad/caliper will get so hot that the brake fluid will boil, causing the pedal to sink down as the fluid expands (which it shouldn't). If you don't encounter brake fade, you aren't using the brake rotor past its true capability.

As far as the "big brake" rotor kits. They replace the rotors with larger diameter rotors. They also replace the pads with larger pads and more powerful calipers. Big brake kits are outrageously expensive and only really only necessary if you are doing some serious racing.

Thanks for the information! I'll check out the sensor.

[SkinnedAussie]

As far as the "big brake" rotor kits. They replace the rotors with larger diameter rotors. They also replace the pads with larger pads and more powerful calipers. Big brake kits are outrageously expensive and only really only necessary if you are doing some serious racing.

Also, there may be clearance problems with the rim. There's nothing worse than having your brake caliper scrape the inside of the rim when you apply the brakes.

[Portis for 6]

Question....

In plain English what's the best way to find a vacuum hose leak?

Thanks.

[twa]

Question....

In plain English what's the best way to find a vacuum hose leak?

Thanks.

With a vacuum leak detector

Use a propane torch(do not light it.)-turn valve on....
Pass the nozzle around your intake tube, vac lines, and all intake connections...

The idle will rise/smooth out when the torch passes a 'leak'

or spray carb cleaner in the same manner

Both of course are flammable so exercise some cautionIE do it in sections with time out for vapor to dissipate

you can also tap a line and put light air pressure and spray soapy water ,but I don't recommend that one.

half the time you can find one by simply feeling the lines

[Portis for 6]

Thanks.

I've tryed feeling, looking, and all that. I'm about to get a can of carb cleaner and try that...

By the way this issue would cause my car to idle at about 2 grand??

[twa]

Could...more info on vehicle might help though

[SpringfieldSkins]

Question....

In plain English what's the best way to find a vacuum hose leak?

Thanks.

In most cases, a vacuum hose leak is audible. You can hear a hissing noise from where the leak is.


A little bit more info now. A combustion engine is basically a big pump. It sucks are in (intake) and blows air out (exhaust). There are also vacuum lines (part of the intake system) that serve several purposes which I won't really get into. If a vacuum line leaks, it's not leaking into the air surrounding the car, it's actually sucking air in. Sometimes, this air will go into the engine unmetered (meaning the CPU doesn't read that it is going into the engine) and will cause the idle to rise or even be rough.


Now based on your problem...

What twa is describing is a great way to find a smaller vacuum leak, perhaps the intake manifold gasket. In order to get the engine to rise up to 2000 RPMs, it would have to be a fairly large vacuum leak. Probably a vacuum leak that you could hear.

If you can't hear a hissing noise and your car is idling at 2000 RPMs, you probably don't have a vacuum leak.


What kind of car is it?

[LaxBuddy21]

Anyone ever replace a starter on a 2006 Pontiac G6? Anyone know where it is located? I have replaced a few starters before but they were pretty obvious. Any help would be appreciated. Google hasnt been very helpful!

[I_Bleed_B&G]

Also, there may be clearance problems with the rim. There's nothing worse than having your brake caliper scrape the inside of the rim when you apply the brakes.

I just put a big brake kit on my car. It looks sweet. I got the caliper powder coated to match my car in pearl white. Here is a sneak peak:

[Mickalino]

Can you recommend a good and effective brand of Radiator Stop Leak ?

One where I don't have to flush out my whole radiator system, hopefully.

[twa]

Can you recommend a good and effective brand of Radiator Stop Leak ?

One where I don't have to flush out my whole radiator system, hopefully.

Alumaweld, but any stop leak is not the preferred option